Disc drives are the primary devices employed for mass storage of computer programs and data. Disc drives typically use rigid discs, which are coated with a magnetizable medium to form a recording layer in which data can be stored in a plurality of circular, concentric data tracks. Typical read/write heads include separate read and write head portions. One advantage to this configuration is that the read and write heads can be optimized for the particular task they are to perform.
The read head typically includes a magnetoresistive or a giant magnetoresistive read element that is adapted to read magnetic flux transitions recorded to the tracks which represent the bits of data. The magnetic flux from the disc surface causes a change in the electrical resistivity of the read element, which can be detected by passing a sense current through the read element and measuring a voltage across the read element. The voltage measurement can then be decoded to determine the recorded data.
The write head includes an inductive writing element for generating a magnetic field that aligns the magnetic moments of the recording layer to represent the desired bits of data. Magnetic recording techniques include both longitudinal and perpendicular recording. Perpendicular recording is a form of magnetic recording in which magnetic moments representing bits of data are oriented perpendicularly to the surface of the recording layer of the recording medium, as opposed to longitudinally along a track of the medium as in the more traditional longitudinal recording technique. Perpendicular recording offers advantages over longitudinal recording, such as significantly higher areal density recording capability. The areal density is generally defined as the number of bits per unit length along a track (linear density in units of bits per inch) multiplied by the number of tracks available per unit length in the radial direction of the disc (track density in units of track per inch or TPI).
Several characteristics of the perpendicular writing element play an important role in determining its areal density recording capability. One important characteristic, is that the writing element must be capable of operating with a recording medium whose recording layer has a high coercivity. The coercivity of the recording layer relates to the magnitude of the magnetic field that must be applied in order to control the orientation of the magnetic moments of the recording layer. A high coercivity leads to high thermal stability and suppresses the effects of demagnetizing fields to allow for higher areal density recordings.
Other important characteristics of the writing element relate to the track width within which the writing element can write bits of data and the linear density at which the writing element can write bits of data along a given track. The track width of the writing element is generally determined by a width of the pole tip of the writing pole. The linear density of a perpendicular writing element is determined, in part, by the thickness or height of the pole tip. In general, the thinner the pole tip, the greater the linear density that can be achieved. The reduction in the thickness of the pole tip also desirably reduces the likelihood of “side writing” where the writing element overwrites data recorded in adjacent tracks when operating at large skew angles. Unfortunately, for conventional writing poles, there are limitations to the amount that the thickness of the pole tip can be reduced.
Typical writing poles have a substantially uniform thickness to the pole tip. Therefore, a reduction to the thickness of the pole tip results in a reduction to the remainder of the writing pole that is adjacent the pole tip. This reduction in thickness diminishes the magnitude of the magnetic field that can be conducted through the writing pole tip and, thus, limits the coercivity of the recording medium on which the writing element can effectively record data. Consequently, such a reduction to the thickness of the writing pole reduces its ability to record data at a high areal density.
A possible alternative to the writing pole having a uniform thickness, is to bevel the writing pole at the pole tip. This configuration allows the majority of the writing pole to have a large thickness while providing the desirable thin pole tip. Computer simulations have indicated that the magnetic field intensity at the pole tip for such a design is substantially increased over writing poles having a uniform thickness. Accordingly, such a beveled writing pole design should have the capability of performing high areal density recordings since it can operate with recording media having a high coercivity. Unfortunately, methods of manufacturing such a beveled writing pole have yet to be developed.
Therefore, a need exists for methods of manufacturing a beveled writing pole of a perpendicular writing element for use in a disc drive storage system.